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AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
  1. AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
  2. AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
  3. AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
  4. AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
  5. AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
  6. AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
  7. AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
  8. AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
  9. AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
  10. AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
  11. AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
  12. AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing

AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing

(17 customer reviews)

Price range: US$29.90 through US$255.00

Key Features
  • Water Content Test
  • LED Readout
  • Brake Fluid Support
Key Features
☰ REQUEST BULK / B2B QUOTERequest B2B Quote
Secure checkoutFast supportBulk ready
AUTOOL AS502

Product Overview

The AUTOOL AS502 is a handheld brake fluid tester for checking the water content percentage in DOT3, DOT4, and DOT5.1 brake fluid. It combines pressure boost detection, normal and expert test modes, a 260mm flexible probe, and a 2.8-inch backlit LCD screen to help users judge brake fluid condition before replacement.

DOT3 / DOT4 / DOT5.1 Water Content Testing Normal / Expert Mode 260mm Flexible Probe
2.8-inchBacklit Display
6V4 × AAA Batteries
10sResponse Time
3 YearsMain Unit Warranty
AUTOOL AS502 brake fluid tester main product image showing pressure boost detection probe compatibility handheld design and backlit display Click to enlarge
AUTOOL AS502 brake fluid tester 3 year warranty image Click to enlarge
Before You Order And Use

Before You Order And Use

Review the brake-fluid type, battery, test interval, probe cleaning, and storage notes before using the AS502 brake fluid tester.

Brake Fluid Water Test

AS502 is designed to test the water content percentage in brake fluid. It is not an engine oil, transmission fluid, or power steering fluid tester.

Routine Check Suggestion

For routine maintenance, checking brake fluid around every 40,000 km is recommended, depending on vehicle condition and service requirements.

Use Supported Fluids Only

Use AS502 with supported brake fluid types. Normal mode is for DOT3, DOT4, and DOT5.1 brake fluid; expert mode is for selected DOT4 brands.

Install 4 AAA Batteries

The tester uses 6V power from 4 × 1.5V AAA batteries. Install batteries with the correct polarity before operation.

Clean The Probe

Wipe the probe clean before each measurement and clean it after use to avoid fluid residue affecting later tests.

Store Dry

If the tester will not be used for a long time, remove all batteries and store the unit in a dry place at normal room temperature.

Key Features

Key Features

AS502 focuses on fast brake fluid water-content testing with pressure boost detection, two test modes, a flexible stainless-steel probe, comfortable handheld control, and a readable backlit screen.

Pressure Boost Detection

Pressure boost detection technology helps improve test stability and supports clearer brake fluid water-content measurement.

Multiple Brake Fluid Support

Normal mode supports DOT3, DOT4, and DOT5.1 brake fluid, making AS502 suitable for common vehicle brake fluid checks.

Normal And Expert Modes

Switch between standard brake-fluid type testing and expert mode for selected DOT4 brands when more targeted fluid selection is needed.

260mm Flexible Probe

The 260mm gooseneck probe helps reach the brake fluid reservoir more easily during vehicle maintenance.

304 Stainless Steel Outer Hose

The probe hose outer layer uses 304 stainless steel for oil resistance, oxidation resistance, and corrosion resistance.

2.8-inch Backlit Display

The 2.8-inch LCD backlit display makes the result easier to read in bright or low-light working conditions.

AUTOOL AS502 pressure boost detection system feature image Click to enlarge
AUTOOL AS502 highly sensitive 260mm probe and 304 stainless steel hose image Click to enlarge
AUTOOL AS502 handheld silicone grip user friendly design image Click to enlarge
AUTOOL AS502 2.8 inch high definition backlit display image Click to enlarge
Compatibility And Fitment

Compatibility And Fitment

AS502 offers two detection modes. Select the correct mode according to the brake fluid type or supported DOT4 brand before testing.

Normal ModeSuitable for DOT3, DOT4, and DOT5.1 brake fluid water-content testing.
Expert ModeSuitable for selected DOT4 brands, including MOTUL, ATE, FERODO, MOBIL, BREMBO, TRW, BOSCH, CASTROL, TOTAL, VALEO, FUCHS, and TEXTAR.
Selection CheckDo not treat expert mode as universal support for every fluid brand. Match the on-screen mode to the fluid being tested.
AUTOOL AS502 brake fluid compatibility normal mode DOT3 DOT4 DOT5.1 and expert mode DOT4 brand list Click to enlarge
Specifications

AUTOOL AS502 Product Specifications

AS502 uses 6V battery power, a 2.8-inch display, 10-second response, pressure boost detection technology, and a 260mm 304 stainless-steel probe hose for brake fluid water-content checks.

Core Specifications
ProductAUTOOL AS502 Brake Fluid Tester
Testing ObjectBrake fluid water content percentage
Detection TechnologyPressure boost detection technology
Operating PrincipleBrake fluid water-content testing
Supported Brake FluidDOT3 / DOT4 / DOT5.1 in normal mode; selected DOT4 brands in expert mode
Display2.8-inch LCD backlit display
Power Supply6V, 4 × 1.5V AAA batteries
Test Duration10-second response
Probe / Test Cable Length260mm / 26cm
Hose Material304 stainless steel outer hose
Operating Temperature-10°C~60°C
ModesNormal Mode / Expert Mode
Auto Power OffAutomatically powers off after 5 minutes of no activity
Main Unit Size175 × 72 × 29mm
Warranty3 years for the main unit; 1 year for included accessories
AUTOOL AS502 specifications image showing 6V power 4 AAA batteries operating temperature and button functions Click to enlarge
Core Specifications
ProductAUTOOL AS502 Brake Fluid Tester
Testing ObjectBrake fluid water content percentage
Detection TechnologyPressure boost detection technology
Operating PrincipleBrake fluid water-content testing
Supported Brake FluidDOT3 / DOT4 / DOT5.1 in normal mode; selected DOT4 brands in expert mode
Display2.8-inch LCD backlit display
Power Supply6V, 4 × 1.5V AAA batteries
Test Duration10-second response
Probe / Test Cable Length260mm / 26cm
Hose Material304 stainless steel outer hose
Operating Temperature-10°C~60°C
ModesNormal Mode / Expert Mode
Auto Power OffAutomatically powers off after 5 minutes of no activity
Main Unit Size175 × 72 × 29mm
Warranty3 years for the main unit; 1 year for included accessories
How To Use

How To Use

Install batteries, clean the probe, select the correct brake fluid type, immerse the probe, and start the test. The screen displays the water content percentage and replacement status.

Install Batteries

Open the rear battery cover, insert 4 × 1.5V AAA batteries with correct polarity, then close the cover securely.

Power On

Long press the power button for more than 2 seconds to turn on the tester.

Clean The Probe

Wipe the probe clean before each measurement to avoid residue affecting the result.

Open The Reservoir

Open the brake fluid reservoir cap and prepare the brake fluid sample area for testing.

Select Fluid Type

Press the selection button to choose DOT3, DOT4, DOT5.1, or an available expert-mode DOT4 brand.

Immerse And Test

Submerge the probe into the brake fluid, press the test button, and read the displayed water content percentage and status indicator.

Result Reading And Use Notes

  • % shows the percentage of water content in brake fluid.
  • OK indicates the brake fluid water content is good.
  • ! indicates a brake fluid water-content warning.
  • × indicates replacement is suggested.
  • 0%-2% is displayed as a pass range, 2%-3% as a warning range, and above 3% as a replacement range.
  • The tester automatically powers off after 5 minutes of no activity.
  • Press and hold the power button for 2 seconds after measurement to turn off the tester.
AUTOOL AS502 operating steps image showing probe cleaning reservoir cap opening fluid type selection probe immersion test start and result display Click to enlarge
AUTOOL AS502 interface introduction image showing battery level water content percentage warning replacement and expert mode areas Click to enlarge
Product Comparison

Product Comparison

Compare AS502 with other AUTOOL automotive oil and fluid analyzers before choosing a tester for brake fluid water content, engine oil quality, transmission fluid, boiling point, or power steering fluid.

AS502 FocusBrake fluid water-content testing with pressure boost detection, 2.8-inch backlit display, 6V power, 10-second response, 26cm test cable, and normal/expert mode support.
AS501 DifferenceAS501 also tests brake fluid water content, but uses a 1.8-inch display, 3V power, and iron oxide hose material.
AS503 / AS505AS503 is for engine oil quality by transmittance. AS505 is for automatic transmission fluid testing by transmittance.
AS506 / AS507AS506 tests brake fluid boiling point. AS507 tests power steering fluid by transmittance.
Decision CheckChoose according to the fluid type and test principle, not only by appearance. AS502 is the right choice when the target is brake fluid water content with normal and expert mode selection.
AUTOOL automotive oil and fluid analyzer comparison chart for AS501 AS502 AS503 AS505 AS506 and AS507 Click to enlarge
Related Products

Related Products

Compare related AUTOOL fluid testers for brake fluid water content, engine oil quality, transmission fluid, brake fluid boiling point, and power steering fluid testing.

Manual And Downloads

Manual And Downloads

Download the AS502 manual for battery installation, button functions, standard and expert mode selection, operation steps, result reading, maintenance, and warranty information.

AUTOOL AS502 brake fluid tester user manual preview Click to enlarge

AUTOOL AS502 User Manual

Open the PDF manual for setup, brake-fluid type selection, result interpretation, probe maintenance, and warranty details.

Download Manual

Need Setup Confirmation?

Contact AUTOOL Store before ordering or testing if you need help confirming battery setup, DOT3 / DOT4 / DOT5.1 compatibility, normal or expert mode selection, result reading, or fluid tester model choice.

Emailsupport@autoolstore.com WhatsApp+86 189 2647 7404
AUTOOL AS502 packing list image showing brake fluid tester retail box and user manual Click to enlarge
What Is In The Box

What Is In The Box

The packing list image shows the AS502 brake fluid tester, retail box, and user manual. Final package contents should follow the actual product option and package received.

Main UnitAUTOOL AS502 brake fluid tester with flexible probe
Retail BoxAS502 product packaging shown in the package image
User ManualAS502 user manual shown in the package image
Battery NoteThe tester uses 4 × 1.5V AAA batteries. Batteries are not shown in the package image; confirm the actual package option before ordering if needed.

Questions And Answers

These answers cover AS502 testing purpose, supported brake fluids, batteries, operation, result reading, maintenance, comparison, and warranty support.

Warranty And Contact

Warranty And Contact

For AS502 battery setup, brake-fluid compatibility, normal or expert mode selection, result reading, probe maintenance, manual download, package confirmation, warranty support, or model selection, contact AUTOOL Store directly.

Pre-Sales And Product Support

Use support if you need help confirming whether AS502 is suitable for your brake fluid type, how to interpret test results, how to maintain the probe, or which AUTOOL fluid tester fits your workshop needs.

  • 3-year warranty for the AS502 main unit and 1-year warranty for included accessories
  • DOT3 / DOT4 / DOT5.1 and expert-mode brand confirmation
  • Battery installation and power setup help
  • Probe cleaning and long-term storage guidance
  • Result reading and replacement-status explanation
  • AS501 / AS502 / AS503 / AS505 / AS506 / AS507 model selection support
Email Supportsupport@autoolstore.com WhatsApp Support+86 189 2647 7404

Customer Reviews

  1. 5
    (17 customer reviews)
    100% of customers recommend this product.
    5 Stars100%4 Stars0%3 Stars0%2 Stars0%1 Star0%

  2. Tamosauskas –

    Cheap and great tool, I would recommend it!

    0 of 0 found this review helpful

  3. Benedict Brown –

    AS502 can test the water content in brake fluid! It’s a great tool and I always trust AUTOOL’s quality!

    0 of 0 found this review helpful

  4. Paddy Patience –

    Being able to accurately determine the water content of my gasoline so I can know how often I can change my oil is a great help in my daily car use!

    0 of 0 found this review helpful

  5. Hitech Motorsport (verified owner) –

    good product good price fast shipping.

    0 of 0 found this review helpful

  6. Bostjan Rozman (verified owner) –

    Very good product

    0 of 0 found this review helpful

  7. Frank –

    I usually use paper test strips for brake – fluid moisture. They’re costly, so this new tester will pay off. Tested ATE DOT 4 brake fluid;.9% moisture in a nearly – new container surprised me.

    0 of 0 found this review helpful

  8. Mick The Brick –

    This little peace of kit could save you hundreds in car repairs, highly recommend!

    0 of 0 found this review helpful

  9. Kris Vincent Lim –

    Good quality product, works well.

    0 of 0 found this review helpful

  10. Stjepan Zoricic (verified owner) –

    AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing

    0 of 0 found this review helpful

  11. Alexander –

    Product description matches. Fast delivery and carefully packaged.

    0 of 0 found this review helpful

  12. Colin Kingsley –

    Very impressed with this tester. The construction feels solid and reliable, and it even came with batteries included, ready to use right out of the box. Shipping was fast, and the product was neatly packaged. Overall, a great value for the price. Highly recommended! ??

    0 of 0 found this review helpful

  13. Boyd Nathaniei –

    First time to use a testing device
    Feeling good and professional
    Seller is very good
    Any problem seller will explain one by one

    0 of 0 found this review helpful

  14. Chasel Yeates –

    I bought this because I recently bought a used car but I wasn’t sure if the brake fluid needed to be changed so I ordered this tool and it’s great, I usually do my own maintenance on my car and it was very convenient to use it to do the test and I found out that my brake fluid did need to be changed.

    0 of 0 found this review helpful

  15. Hayden Marion –

    The brake fluid test data is very accurate. Since brake fluid absorbs water very easily, I think it is very necessary to purchase this machine. I tested several types of brake fluid and compared the results with old brake fluid. The data is reliable and trustworthy. Furthermore, I understand that AUTOOL obtained this data through extensive repeated experiments, so I have great confidence in this brand.

    0 of 0 found this review helpful

  16. Cole –

    This brake fluid tester determines whether the car’s brake head needs to be replaced by detecting the water content of the brake fluid. When used with a brake fluid replacement machine, the number of times the brake fluid needs to be replaced is much faster.

    0 of 0 found this review helpful

  17. Vladyslav –

    I am very satisfied with the AUTOOL AS502 I purchased. The device is compact and easy to operate. It can determine whether the brake fluid needs to be replaced by testing the water content of the brake fluid. It is a very practical product.

    0 of 0 found this review helpful

  18. Jonah Hofmann –

    The AS502 perfectly meets my needs. My car has recently been experiencing issues with insufficient brake pressure and soft brakes. After searching online, everyone gave me advice on whether I need to replace the brake fluid. This device tests the water content in the brake fluid to determine whether my car’s brake fluid needs to be replaced. It’s easy to operate and suitable for novices.

    0 of 0 found this review helpful
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AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing
AUTOOL AS502 Car Brake Fluid Tester For Water Content Testing

Price range: US$29.90 through US$255.00

Add to cart This product has multiple variants. The options may be chosen on the product page